Merge Multiple CSV Files Learn more

Append any number of large CSV files into one. Drop them all at once or add one by one. Handles massive files that crash Excel or Google Sheets. Streamed locally in your browser.

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Skip header row from all files except the first

Merging... 0%

Merge Complete

Files Merged

Total Rows

Output Size

Time (sec)

Files are processed in streaming chunks. Even 500MB+ CSVs work. First file's header is kept; subsequent headers are skipped. Drag to reorder. Nothing leaves your browser.

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Merge Multiple CSV Files

What this solves

Merging any number of huge CSV files that crash Excel or Google Sheets
Simple row append: File 1 rows, then File 2 rows, then File 3, etc.
Header row is kept from the first file; skipped from all others by default

How to use

Drop all your CSV files at once, or browse and add more
Drag to reorder files in the queue
Click "Merge All Files" to combine them
Download the merged output as a single CSV

Privacy

Everything runs locally using the File API and streaming chunks
No data is uploaded to any server